The present invention relates to an improvement in pneumatic circuits for controlling the movement of pneumatically propelled vehicles along a track or line that has several stations.
A system for the pneumatic propulsion of cargo or passenger vehicles is disclosed in Brazilian Pat. No. 7,703,372, filed on May 25, 1977 (25.05.77). This system consists of a tube equipped with a longitudinal slot with a sealing system through which passes a rod or shaft attached to a set of fins on the chassis of the vehicle, supported by the tube, with the propulsion being provided by means of an airflow of high-speed acting on the set of fins, propelling it and, as a result, moving the vehicle freely, by means of devices that are adequate to enable this movement/motion, with the flow in question being generated by stationary sources located outside the vehicle, with the system in question also including brakes that act directly on the said devices and special conduits for enclosing the electrical and telephone network cables.
The pneumatic propulsion system described above for the transport of cargo or passengers is characterized by the fact that the vehicles are propelled pneumatically by means of stationary units, inasmuch as the system has the following goals: to provide an urban transportation system on a scale that meets current and future needs; to combine, in a single design, optimal characteristics in terms of vehicles, permanent trackway, and terminals; to provide significant progress in economic effectiveness in urban transportation; and to provide speed, regular service, comfort, and safety at reduced costs.
Brazilian Pat. No. 7,906,255, filed on Sep. 28, 1979 (28.09.79), proposed an improvement in a pneumatic propulsion system for cargo vehicles and passenger vehicles. This improvement consisted of a propulsion duct which, in addition to serving as a channel for air for the propulsion of the vehicle, also had the additional function of providing the necessary structure for installation in the elevated network of the transportation system, i.e., its own structure for the propulsion duct, consisting of a single channel in conjunction with tracks or rails forming an integral part of the said structure, thereby making unnecessary any other structures for the support of the rails, except the structures for supporting or keeping the main structures above the ground, spaced at sufficiently large intervals so as not to interfere with surface traffic.
Another important characteristic of the system is that when a suction regime is established in the duct, the difference between the internal and external pressure acts to compress a flexible flap against a stop, sealing the longitudinal slot in the duct, and at the same time allowing the passage of the articulation arm of the fin of the vehicle through a mechanical gap, such that because of its flexibility, this flap provides an adequate seal even under over-pressure conditions in the duct, with a system also being provided for the relief of the internal pressure within the propulsion duct.
The system in question is also equipped with a flow alternator mounted in conjunction with each blower, in combination with a flow control valve, by means of which the airflow conditions within the duct can be controlled, which in turn determine the back and forth movements of the vehicle by remote control, as a function solely of the commands issued to the flow alternator. The system in question also includes a set of valves at each station, positioned such that they provide control means for a safety system that ensures the positive separation of two vehicles under any circumstances.
Brazilian Pat. No. 83 01 706, filed on Apr. 4, 1983 (04.04.83), describes improvements in a pneumatic propulsion system for cargo vehicles and/or passenger vehicles. In the pneumatic propulsion system in this invention, the vehicle is controlled through the regulation of the airflow in the propulsion air duct, with this type of regulation being implemented by means of butterfly-type control valves, in association with a single airflow generator. Through their position, these valves determine the direction of the airflow in the duct, its speed, and the pressure differential (within the discharge and pressure range of the generator unit). A set of four valves associated with the generator unit connects the suction and exhaust manifolds to the air propulsion duct and to the atmosphere.
The documents cited above do not provide sufficient means for adequate control of the movements of vehicles along the line. The operation of a pneumatically controlled propulsion transportation system requires that control elements be provided for maintaining adequate vehicle frequency, regulating vehicle traffic, ensuring the effective movement of vehicles over the entire length of the line, and establishing safe conditions for the vehicles during operation, along with other equally important factors.
The goal of the present invention is an improvement in a control circuit for the operation of pneumatic propulsion vehicles, so that these vehicles can be adapted to the widest possible range of situations applicable in a transportation system, meeting requirements and objectives such as the ones listed below, i.e.:
Maintaining an adequate frequency between vehicles in order to provide the transportation capacity and the level of transportation service required in each application;
Arranging the propulsion elements in such a way as to allow different locations to for the power propulsion units as a function of the spaces available in each application site, bearing in mind the fact that the power propulsion units are volumetrically the largest elements in the propulsion system;
Obtaining different levels of intensity for the propulsive thrust, for example, by combining the action of one or two power propulsion units, simultaneously or not, depending on the performance required from the vehicle under various load conditions;
Establishing safe conditions for the vehicles in operation simultaneously on a single line, by means of independent propulsion circuits;
Obtaining redundancies in the propulsion system in order to continue the operation of vehicles in the event of a failure in one or more pieces of equipment in the propulsion system;
Adding atmospheric valves located at specific points along the line, so that the duct can be opened or closed to the atmosphere without interfering with the inside space of the propulsion duct, while improving the controllability of the propulsion system and creating on the airflow circuits within the duct;
Making it possible for vehicles to depart at the same time from two contiguous stations;
Making it possible for vehicles to reach their respective stations at the same time;
Making it possible for one vehicle to arrive at a station while another vehicle is moving in the preceding section;
Making it possible for one vehicle to arrive at a station while another vehicle is moving in the section between stations, with a third vehicle being stopped at the next station for boarding or loading and unloading;
Making it possible for one vehicle to be located at a station while a second vehicle is in motion in the section ahead and a third vehicle is stopped at the next station;
Adding assemblies consisting of section isolation valves and atmospheric valves, appropriately located throughout the length of the line, with the valves being operated in a given sequence and at given timing, thereby making it possible for the section isolation valve to be closed or open during periods when the duct is not being pressurized by an airflow, thereby allowing such valves to be actuated with minor forces, and also allowing the system to operate safely by preventing a vehicle""s propulsion plate from hitting the shutter of the section isolation valves and atmospheric valves proposed in the earlier patents; and
During the vehicle deceleration phases, the arrangement of atmospheric valves, section isolation valves, and/or power propulsion units, depending on the circumstances, so as to make it possible to avoid the use of propulsive force, which would be applied only when necessary and in instances when the vehicle is in forward motion; that is, the propulsion system is not used (and therefore no motive power is consumed) to brake the vehicle by means of a pressurized airflow acting against the vehicle movement. The vehicle is decelerated without consuming propulsion power, for this purpose relying instead on the partial or total closure of the propulsion duct in the section in which the vehicle is located, using a combination of the flow control valves in the power propulsion unit and/or the atmospheric valves. As a complement to the braking force of the vehicle, a friction brake is applied to the wheels. The atmospheric valves, or a combination of to the positions of the airflow control valves in the power propulsion unit are used to implement the connection between the propulsion duct and the atmosphere, allowing movement (when necessary) of the vehicle without pneumatic resistance from the propulsion system.
Another goal of the present invention is to create safe conditions for the passive deceleration and braking of a vehicle on the end of the line in the event that the vehicle inadvertently enters this portion of the line. To do so, safety circuits are used by providing an additional extension of the propulsion duct, closed at the end with a plug, so that the set consisting of the vehicle propulsion plate, the line duct,.and the plug at the end of the duct function as a system that stops the progress of the vehicle, thereby providing a damping action due to the compression of the air.
The invention also includes an improvement in the power propulsion unit consisting of connecting this unit to the propulsion duct of the guideway by means of a single opening on the guideway duct and using a combination of positions for the airflow control valves, all closed, or in such a way as to connect the duct to the atmosphere without, however, generating an airflow, thereby allowing the power propulsion unit to operate in the same way as an atmospheric valve, i.e., either opening or not opening the duct to the atmosphere.
The invention includes improved atmospheric.valves connected to the propulsion duct, which, when necessary, allow the pressure in the duct to be relieved. The atmospheric valves are located appropriately along the length of a given segment of the line. At the same time, these atmospheric valves, either in open or closed position, allow the vehicle to move in such a way that it passes beyond the location of these valves without obstructing the propulsion plate of the vehicle within the duct by any type of shutter or obturator, thereby allowing the system to be controlled by means of several possible configurations for valves and power propulsion units.
In order to allow full understanding of the improvement in the control circuit for the operation of pneumatically propelled vehicles which is the object of the present invention, the following such improvement is described in detail, with reference to the attached drawings: